What causes albinism?

Albinos—people with white hair and skin, and often reddish eyes—are being mutilated and murdered for their body parts in Tanzania, according to The New York Times. Sometimes as family members look on in horror, groups of machete-wielding men have chopped off the legs, heads, and genitals of albinos.

Among the dead: a seven-month-old baby, a cassava farmer with two children, and a child murdered by his own father, according to reports by the BBC. The brutal killings -- 40 since 2007 -- are fueled by rumors that albino blood, skin, and hair have magical powers. People are actually weaving albino hair into their fishing nets and fashioning amulets with albino body parts, hoping that these devices will bring them riches, The Times reports in a story profiling Canadian albino Peter Ash, founder of Under the Same Sun, an albinism advocacy organization aimed at shaming the Tanzanian government into stopping the murders.

The horrifying scenes pile onto the day-to-day issues albinos face: Albinism is a debilitating condition that causes vision loss, extreme sun-sensitivity, and sometimes embarrassment and stigma. Albinos have long been villainized in literature and pop culture—think Silas, the evil monk in The Da Vinci Code, or the nefarious blond twins in The Matrix Reloaded.

So what causes albinism, and are there any treatments? To find out, we checked in with Raymond Boissy, a professor of dermatology at the University of Cincinnati College of Medicine.

[An edited transcript of the interview follows.]

What is albinism?
Albinism is a disease in which a person has partial or complete loss of pigmentation (coloring) of the skin, eyes and hair.
What causes it?
Genetic mutations that affect the production of a pigment called melanin. There is a cell called the melanocyte that is responsible for giving skin, hair, and eyes pigmentation. In albinism, the melanocytes are present, but genetic mutations interfere with their pigment production or their ability to distribute it to keratinocytes, the major cell type comprising the epidermis, or outer layer of the skin. There are currently five known genetic types of albinism, the most common being oculocutaneous type 1 (OCA1) and type 2 (OCA2). Oculocutaneous means affecting the eyes and skin ("oculo" meaning eye and "cutaneous" meaning skin).

Patients with OCA1 have mutations in a gene called TYR that is responsible for creating the enzyme tyrosinase, used by cells to convert the amino acid tyrosine into pigment molecules that color the skin, hair, and eyes. OCA2, the most common form of albinism in Africa, results from a mutation in the OCA2 gene, which encodes the P protein. We don't know what this P protein does.

What does a person with albinism look like?
Most people with OCA1 have snow-white skin, snow-white hair, and no pigment in their eyes. The iris (colored part of the eye that encircles the pupil) is a pale bluish pinkish color, while the pupil may actually be red. This redness comes from light entering the pupil and reflecting off of blood vessels in the retina, the light-sensitive layer of tissue lining the back of the eyeball. Normally, the pupil appears black because pigment molecules in the retina absorb light entering the eye, preventing it from bouncing back to the outside world.

Those with OCA2 can make a small amount of pigment and thus may have light blond to brown hair color. Their irises are blue to light gray and their pupils dark red to light gray.

How does this lack of pigment in the eyes affect vision?
People with albinism are legally blind because photoreceptors (cells in the retina that detect light) get oversaturated with light and send confusing messages to the brain. If you look at a person with albinism, you'll see a nystagmus, or fluttering, in their eyes; the eyes are sort of bouncing in their sockets because they are getting a confusing visual stimulus.
What are some other conditions associated with albinism?
Without pigment in the skin, you are more susceptible to non-melanoma skin cancers in keratinocytes. Normally, melanocytes distribute pigment molecules to keratinocytes, where they act sort of like umbrellas shielding the nucleus (and the DNA inside) from the sun's UV radiation. Albinos are particularly at risk for squamous cell carcinoma, a cancer of the outermost layer of skin, and basal cell carcinoma affecting deeper layers. They also may experience premature skin aging. Melanin helps prevents wrinkles and elastosis (breakdown of elasticity) by blocking UV radiation.

Are there any treatments for albinism?
No, there are not. Patients with albinism are advised to protect themselves from the sun.
Are there any treatments in the pipeline?
Some researchers, such as Richard King at the University of Minnesota, are trying to develop gene therapies, or drugs that would go into the cells and correct DNA mutations responsible for albinism. So far, scientists have had some success in correcting patches of depigmented skin and hair in mice, but they are a long way from translating this research to humans.

What animals, besides humans, can be albinos?
Any animal that has melanocytes can get albinism. That means virtually all mammals. Reptiles, amphibians and lower vertebrates can also be albinos, but these organisms may also have other types pigment production cells besides melanocytes, so they may not appear colorless. In the zoo here in Cincinnati, we had an albino alligator.